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Eugene P. Goldberg, Paul Martin, Amin Elachachabi, Hung-Yen Lee, Khalid Mentak; Nanosurface Properties of Foldable Intraocular Lenses. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6675.
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© ARVO (1962-2015); The Authors (2016-present)
A number of diferent proprietary crosslinked acrylic copolymers are used clinically for intraocular lens (IOL) implants. Although they have been in use for many years to replace the cataractous natural lens, there are almost no reports on their physical, chemical, and surface properties which might affect their functional performance. Since biocompatability can depend significantly on the acrylic lens nanosurface, several important nanosurface properties were investigated.
Studies are reported here for four IOL polymers in clinical use encompassing (1) lens wetting and surface energy (2) nanosurface morphology as observed by atomic force microscopy (AFM) (3) surface physical properties (i.e. modulus and hardness) measured by a nanoindentation procedure and data analysis method developed in our laboratory for low modulus polymers and (4) in vitro measurement of human ocular capsule epithelial cell adhesion to the IOL polymer surfaces.
Although the four different low Tg acrylic copolymers are usually referrred to as "hydrophobic", they actually were found to exhibit varying degrees of hydrophilicity and become increasingly so upon immersion in aqueous media. Significant changes in nanosurface morphology occur in going from the dry to hydrated states upon aqueous immersion. Nanoindentation experiments using a Hysitron Triboindenter with Triboscan software afforded new surface data.
Large differences in surface modulus ranging from values as low as 0.24 MPa to as high as 11.0 MPa and remarkable changes in AFM nanomorphology occur. Epithelial cell adhesion decreases as surface hydrophilicity increases. These new data suggest that such large differences in foldable IOL nanosurface properties may prove important to the safe handling and clinical performance of foldable acrylic IOLs.
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